In general, thermal power generation using fossil fuel and atomic power generation using nuclear fission can be considered as typical types of power generation.
However, the thermal power generation has a problem that it causes environmental pollution because it uses energy produced by burning fossil fuel and it requires a large amount of construction costs. The atomic power generation is advantageous in producing a large amount of power, but it also requires a large amount of costs for facilities for preventing leakage of radiation. Further, an atomic power plant is considered as a dangerous facility, so it is necessarily accompanied by strong opposition by residents even from the step of preparing construction. In addition, waste treatment is difficult and even a small accident always has possibility of severe ecocide.
Accordingly, as an alternative to thermal power or atomic power natural energy sources such as wind force, tidal power, water power, and solar heat, which do not cause environmental pollution, have attracted attention as not only as clean energy sources, but also as a permanent and inexhaustible energy sources.
However, water power generation, a typical type of natural power generation, does not cause environmental pollution, but requires great cost when a dam is built for blocking water. Further, when a dam is constructed, it is accompanied by changes in the ecosystem due to wide areas being submerged, and if the ecosystem changes are severe, they may even cause a secondary environmental problem of changing the climate of the area. Further, wind power generation and solar power generation are influenced by weather conditions, so it is impossible to generate power when there is no wind or when solar radiation energy is blocked.
On the other hand, there is OTEC (Ocean Thermal Energy Conversion), which is another type of power generation using clean energy.
OTEC, which employs a power generation system using heat of vaporization and heat of condensation from surface water at a high temperature and deep water at a low temperature, does not produce carbon because it takes energy only from the seawater, and the seawater can be used as an infinite recyclable energy source.
Marine facilities that can generate power on the sea are necessary for OTEC and those marine facilities can be floated on the sea by floats with a predetermined area ensured.
A technique relating to installation of marine facilities has been disclosed in Korean Patent Application Publication No. 10-2013-0131121. Korean Patent Application Publication No. 10-2013-0131121 proposes a ‘Floating production storage and offloading’, which includes a lower floating structure having a predetermined space and at least one column disposed on the lower floating structure, with a lower portion inside the lower floating structure.
However, such a floating structure may be moved in a heaving, pitching, rolling, or yawing fashion by waves or surges. Such movement of the floating structure may have an adverse influence on control and operation of the marine facilities on the float.
Further, when an artificial island is constructed on the sea or there is a need for a large scale marine facility, there is a limit in increasing the size of a floating structure and it is also difficult to construct a floating structure because floating structures are generally complicated.